A reader reminds me that instead of the lion joke below I could have used this exchange from the Simpsons:
Homer: No bears since the bear patrol.
Lisa: Dad, that’s rather specious reasoning.
Homer: Thank you honey.
Lisa: No Dad, I could just as easily say that this rock keeps tigers away.
Homer: How does it work?
Lisa: It doesn’t, but you don’t see any tigers around do you?
Homer: Lisa, I’d like to buy that magic rock.